1. Field of the Invention
The present invention relates to a suspension for vehicles.
2. Description of the Related Art
There are two types of independent suspension systems generally used in vehicles: namely, a system known as strut-type suspension and a system known as double-wishbone-type suspension.
As shown in FIG. 20, the strut-type suspension has a strut 53 which is connected at its upper end to the chassis of a vehicle, a carrier 54 connected to the strut 53, and a control arm 55 connected between the carrier 54 and the chassis. This type of suspension is advantageous in that it can easily be mounted on vehicles because it requires a comparatively small installation space. On the other hand, this type of suspension is disadvantageous in that it allows only a small change in camber and has only a small degree of freedom in the geometric setting such as roll center.
The double-wishbone-type suspension, which also finds extensive use, has an upper control arm and a lower control arm which are provided between the carrier and the chassis. This type of suspension offers a large degree of freedom in the geometric setting but requires a comparatively large installation space. In addition, this type of suspension is difficult to mount on vehicles.
Under these circumstances, Japanese Patent Laid-Open No. 56-82613 discloses a vehicle suspension which has advantages offered by both types of suspension mentioned above, namely, a reduced installation space, easy mounting on vehicles and a large degree of freedom of geometric setting. In this improved suspension, as shown in FIG. 21, the point 58 of pivotal connection between the lower arm 56 and the strut 57 is located near the center of the lower arm. In this arrangement, therefore, a large camber angle is obtainable by reducing the length of the upper arm 59. However, there is a practical limit in the reduction of the length of the upper arm because the reduced upper arm length increases the tendency of buckling. Consequently, the degree of freedom for assuring a large change in the camber angle is limited.